I concur.
The plants look ion-hungry.
And I am always amazed at how much cal and mag Cannabis plants like.
I'm a big fan of cal-mag.
@JSheeze
I have used nitric acid as a veg pH-down and phosphoric as a flower pH-down. My stock of nitric is gone, so phosphoric has done all pH-down duty in my last grows. The acid should be a small fraction of total N or P, so I don't think of it as changing nutrient levels.
As for pH, the Golden Rule is that [H3O+] times [OH-] always equals 10 to the minus 14 (units become moles squared per liter squared, so the units are thrown out by universal chemists' convention of venality). This is a basic property of the solvent we choose: water.
As pH and pOH are sign-flipped exponents, pH and pOH always add up to 14.
Alkaline, to a general chemist, means "a pH greater than 7". I remember when shampoos were being marketed as "non-alkaline" in the '70s, and that just meant " a pH less than 7".
From what I infer, alkalinity to a hydrologist is something different ... a buffering capacity expressed in mmol per liter. I imagine that it takes x mmol/l to achieve a neutral pH, which is used as a marker for "total alkalinity" but not its measure.
So yes. A pH of 6 means "hydrogen ion concentration of ten to the minus 6 molar" and necessarily "hydroxide ion concentration of ten to the minus 8 molar", as 14 minus 6 is well you get it.
Heehee, instructing collegians in chemistry does come in handy every now and then!
Not sure about the sodium oxide question.
Magnesium sulfate heptahydrate is 10.0% magnesium by weight. Thus, adding one gram of Epsom salt to a 100-liter res will bump its [Mg] by one PPM. In my twenty-liter batches, 5 grams gave a 25-ppm Mg boost. The S doesn't hurt either.